The present invention relates generally to a method and device for generating a signal that emulates the pattern of light reflected from a bar code when a pulse of light from a bar code scanner is applied to the bar code, and, more particularly, to a device that communicates with bar code scanners without the physical printed barcode.
Bar codes have been in use for many years and have become the standard for efficient and inexpensive coding and transfer of small amounts of data. The Universal Product Code (UPC), a bar code symbology standard, has become an indispensable merchandising system to identify manufacturers and products. There are many bar code standards available including the UPC, the European Article Number (EAN), Code 39, Code 93, Code 128, ISBN, and ISSN to name a few. Each standard has a specific symbology to code information, but every standard functions on the same basic bar and space premise. A bar code is comprised of a series of alternating black bars and white spaces of varying widths. Each bar and a space will have a minimum width that can be treated as the unit width for a bar and a space, respectively. At least one bar and one space of respective unit width typically appear at the beginning of each bar code sequence for proper calibration. Successive bar and spaces in a coded sequence will have widths that are integer multiples of the unit width and the bar code information is coded by the pattern of varying widths in a sequence of alternating bars and spaces. The bar code sequence can be printed on a medium and affixed to a product or item for identification.
The bar code can be read and decoded by a bar code scanner signal that passes a pulse of light over a printed bar code and detects the back-scattered light patterns reflected by the bar code. A bar will absorb a large portion of the scanner signal while a space will reflect a large portion of the scanner signal. The durations of the absorption and reflectance patterns gathered by the scanner as back-scattering of the scanner signal corresponds to the widths of the corresponding bars and spaces of the bar code. It will be noted that CCD readers quantize an image and perform bitwise analysis to distinguish marks from spaces, and vice versa, and do not sense impulses of light. In either way, the coded information is transferred from the printed bar code to the scanner. All bar code standards operate in this fashion
Bar codes have been used in automated shipping and packaging systems. In some instances, bar code readers are used extensively along a conveyor line to provide information to an operator as to where certain products are in the line. However, some bar code readers are virtually inaccessible to operators while machinery, associated with the automated shipping and packaging systems, is running. For example, in clean rooms associated with packaging semiconductors, operator presence is often restricted. Therefore, if a bar code reader is not operating properly because of a fault, the bar code reader may not properly indicate a fault occurrence such as an absence of semiconductor wafers from the line because of a fall therefrom, for example. Furthermore, printed bar codes do not allow data represented thereon to be easily changed to verify proper fault reporting by the bar code readers.
Accordingly, a method and system to simulate bar code labels having data that can be automatically and easily changed is desired.